U.S. patent application number 17/532957 was filed with the patent office on 2022-03-17 for temperature control system.
This patent application is currently assigned to WARMUP PLC. The applicant listed for this patent is WARMUP PLC. Invention is credited to Svetoslav Angelov, Spencer Sheen, Antony White.
Application Number | 20220082269 17/532957 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-17 |
United States Patent
Application |
20220082269 |
Kind Code |
A1 |
White; Antony ; et
al. |
March 17, 2022 |
TEMPERATURE CONTROL SYSTEM
Abstract
A support structure for a heating or cooling system includes a
plurality of projections designed to be capable of retaining one or
more thermal elements positioned adjacent thereto. The projections
are positioned so as to form a first set of substantially parallel
undulating channels, each channel having one of the projections
forming at least a part of the inner radius of each undulation,
with each projection having a recess formed in a side wall thereof
facing said channel. The undulations of the channel ensure that a
thermal element positioned in the channel will make contact with
the projections each time it has to bend around one, without
requiring spacing of the projections to squeeze the thermal
element. The thermal element can thus be held securely without any
play (unwanted lateral movement) in a channel that is slightly
wider than the thermal element. Recesses in the channels at the
contact points also restrict movement in the vertical direction,
thus preventing the thermal element from `popping out` of the
channel, while not requiring any restriction narrower than the
thermal element.
Inventors: |
White; Antony; (London,
GB) ; Sheen; Spencer; (London, GB) ; Angelov;
Svetoslav; (London, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WARMUP PLC |
London |
|
GB |
|
|
Assignee: |
WARMUP PLC
London
GB
|
Appl. No.: |
17/532957 |
Filed: |
November 22, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15919433 |
Mar 13, 2018 |
11181283 |
|
|
17532957 |
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International
Class: |
F24D 13/02 20060101
F24D013/02; F24D 3/14 20060101 F24D003/14; F24D 3/12 20060101
F24D003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2018 |
GB |
1800924.1 |
Claims
1. A heating system comprising: a support structure having a
plurality of projections formed thereon; and a heating wire;
wherein the plurality of projections form a first set of
substantially parallel undulating channels on the support
structure, the undulations of each channel being formed by a series
of constrictions that are alternately offset in opposite directions
along a length of the respective channel; wherein the heating wire
is configured to be retained within one or more of the
substantially parallel undulating channels formed on the support
structure; and wherein at least a portion of the support structure
is textured.
2. The heating system of claim 1, wherein the texture on the
support structure is formed by one of molding, surface imprinting,
etching, or grit-blasting.
3. The heating system of claim 1, wherein the texture on the
support structure comprises fibers adhered to or partially melted
into the support structure.
4. The heating system of claim 3, further comprising a fabric
stress mitigation layer on an underside of the support structure;
wherein the fabric stress mitigation layer comprises fleece fibers;
and wherein the fibers adhered to or partially melted into the
support structure are fleece fibers of the same type as the fleece
fibers of the fabric stress mitigation layer.
5. The heating system of claim 1, wherein: each projection of the
plurality of projections comprises a side wall having a recess
formed therein, the recess facing one of the substantially parallel
undulating channels formed on the support structure; the heating
wire undulates within the one or more of the substantially parallel
undulating channels when the heating wire is retained therein; each
undulation of each of the substantially parallel undulating
channels has an amplitude that does not exceed a width of the
respective channel; the projections of the plurality of projections
are grouped into pairs; and the recesses of each pair of
projections face adjacent undulating channels of either the first
set of undulating channels or a second set of undulating
channels.
6. The heating system of claim 5, wherein the projections of each
pair of projections are separated by a portion of the support
structure.
7. The heating system of claim 5, wherein: each pair of projections
has one of two orientations, one orientation being a ninety degree
rotation of the other orientation; the pairs of projections are
arranged on the support structure in a rectangular grid with the
orientations of the pairs of projections being set according to a
checkerboard pattern; in a first one of the two orientations, the
pairs of projections form a structure that is wider in a first
dimension than in a second, perpendicular dimension; and in a
second one of the two orientations, the pairs of projections form a
structure that is wider in the second dimension than in the first
dimension.
8. A heating system comprising: a castellated mat having a
plurality of projections on an upper side thereof; and a heating
wire; wherein the plurality of projections form a first set of
channels on the castellated mat; wherein the heating wire is
configured to be retained within one or more of the channels formed
on the castellated mat; and wherein at least a portion of the
castellated mat is textured.
9. The heating system of claim 8, wherein the texture on the
castellated mat is formed by one of molding, surface imprinting,
etching, or grit-blasting.
10. The heating system of claim 8, wherein the texture on the
castellated mat comprises fibers adhered to or partially melted
into the castellated mat.
11. The heating system of claim 10, further comprising a fabric
stress mitigation layer on an underside of the castellated mat;
wherein the fabric stress mitigation layer comprises fleece fibers;
and wherein the fibers adhered to or partially melted into the
castellated mat are fleece fibers of the same type as the fleece
fibers of the fabric stress mitigation layer.
12. The heating system of claim 8, wherein: the first set of
channels comprises a first set of substantially parallel undulating
channels; the undulations of each channel are formed by a series of
constrictions that are alternately offset in opposite directions
along a length of the respective channel; each projection of the
plurality of projections comprises a side wall having a recess
formed therein, the recess facing one of the substantially parallel
undulating channels; the heating wire undulates within the one or
more of the substantially parallel undulating channels when the
heating wire is retained therein; each undulation of each of the
substantially parallel undulating channels has an amplitude that
does not exceed a width of the respective channel; the projections
of the plurality of projections are grouped into pairs; and the
recesses of each pair of projections face adjacent undulating
channels of either the first set of undulating channels or a second
set of undulating channels.
13. The heating system of claim 12, wherein the projections of each
pair of projections are separated by a portion of the castellated
mat.
14. The heating system of claim 12, wherein: each pair of
projections has one of two orientations, one orientation being a
ninety degree rotation of the other orientation; the pairs of
projections are arranged on the castellated mat in a rectangular
grid with the orientations of the pairs of projections being set
according to a checkerboard pattern; in a first one of the two
orientations, the pairs of projections form a structure that is
wider in a first dimension than in a second, perpendicular
dimension; and in a second one of the two orientations, the pairs
of projections form a structure that is wider in the second
dimension than in the first dimension.
15. A method of forming a support structure for a heating system,
the method comprising: forming a castellated mat having a plurality
of projections on an upper side thereof, the plurality of
projections forming a first set of channels that are configured to
retain a heating wire; and texturing at least a portion of the
castellated mat.
16. The method of claim 15, wherein the step of texturing at least
a portion of the castellated mat comprises one of molding or
surface imprinting the texture onto a surface of the castellated
mat during a vacuum forming process.
17. The method of claim 15, wherein the step of texturing at least
a portion of the castellated mat comprises one of etching or
grit-blasting a surface of the castellated mat after the step of
forming the castellated mat.
18. The method of claim 15, wherein the step of texturing at least
a portion of the castellated mat comprises: applying fibers to a
surface of the castellated mat after the step of forming the
castellated mat; and allowing the fibers to partially melt into the
surface.
19. The method of claim 18, further comprising the step of
providing a fabric stress mitigation layer comprising fleece fibers
on an underside of the castellated mat.
20. The method of claim 19, wherein the fibers applied to the
surface of the castellated mat are fleece fibers of the same type
as the fleece fibers of the fabric stress mitigation layer.
21. The method of claim 20, wherein the fibers applied to the
surface of the castellated mat are supplied from off-cuts or
wastage from the step of providing the fabric stress mitigation
layer.
22. The method of claim 15, wherein the step of texturing at least
a portion of the castellated mat comprises adhering fibers to a
surface of the castellated mat after the step of forming the
castellated mat.
23. The method of claim 22, further comprising the step of
providing a fabric stress mitigation layer comprising fleece fibers
on an underside of the castellated mat.
24. The method of claim 23, wherein the fibers adhered to the
surface of the castellated mat are fleece fibers of the same type
as the fleece fibers of the fabric stress mitigation layer.
25. The method of claim 20, wherein the fibers adhered to the
surface of the castellated mat are supplied from off-cuts or
wastage from the step of providing the fabric stress mitigation
layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/919,433, filed on Mar. 13, 2018, which
claims priority under 35 U.S.C. .sctn. 119 to United Kingdom Patent
Application No. 1800924.1 filed on Jan. 1, 2018, the contents of
which are hereby incorporated by reference in their entirety.
TECHNICAL FIELD
[0002] The invention relates to heating and cooling systems for use
within floors, walls or ceilings of buildings. In particular it may
relate to underfloor heating systems in which heating is provided
by heating cables or pipes fitted to a mat or panel.
BACKGROUND
[0003] Heating and cooling systems which use the floor, wall or
ceiling surface as the heat exchange surface require either an
embedded heat source or heat sink, commonly in the form of
electrically resistive heating cables, or an embedded distribution
system of pipes carrying a fluid or gas, that has been either
heated or cooled by a connected heat source or heat sink. These may
hereafter be referred to as the thermal element(s). While a
plurality of thermal elements may be used, it is common for a
single thermal element (e.g. a single cable or a single pipe) to be
used. A single thermal element is typically laid in a serpentine
fashion on the floor so as to distribute its heating or cooling as
evenly as possible.
[0004] To ensure a regular temperature distribution of the emitting
surface, it is important to space the thermal element at
equidistant intervals, e.g. by looping back and forth across the
emitter area.
[0005] The act of heating and/or cooling these exposed surfaces
produces shear stress coplanar to the isotherms, created by the
thermal element while it is active. This sheer stress can cause
mechanical failure of the construction if it exceeds the limits of
any individual material or bond within the system construction.
[0006] Some underfloor heating installations employ an intermediate
structure fitted between a main floor and a sub-floor. The main
floor is the upper structure that is presented to the user and is
typically a decorative floor layer, e.g. tiles, solid wood,
laminate, etc. The sub-floor is the main structural floor of the
building and is typically either concrete or wood. The intermediate
structure provides support for the main floor as well as providing
protection for the wires or pipes which are laid therein (e.g.
protection from footfall during installation and protection from
crushing after installation).
[0007] Heating and cooling systems, whether electrical or hydronic
(water based), need to accommodate expansion and contraction of the
various structural elements of the installation. Such movement may
be due to temperature variations (e.g. during start-up and
cool-down of the heating elements) or due to drying out of
structures after installation (e.g. drying of concrete or timber
leads to shrinkage). The main area of stress in a traditional
installation is between the sub-floor and the intermediate
structure as this is typically where the greatest temperature
difference occurs due to contact with the ground (or other
surfaces), and is also where contraction due to drying will occur.
Thermal stresses are dependent on the temperatures, thermal
conductivities and thermal expansion coefficients.
SUMMARY OF THE INVENTION
[0008] The intermediate layer, or support layer is often provided
in the form of one or more mats that can be rolled out or tiled
over the underlying subfloor. The support layer typically has a
plurality of projections designed to be capable of retaining one or
more thermal elements positioned adjacent thereto. Such structures
are often referred to as castellated structures. The projections or
castellations typically form a series of pillars around or between
which the thermal elements are threaded, the projections providing
support to hold the thermal elements in position along straight
runs, but also providing support for changes of direction by
winding around the projections (e.g. a 90 degree wind to change to
a perpendicular direction). The projections may be spaced such that
they grip the thermal elements firmly to prevent lateral as well as
vertical movement, thus holding them securely in place during
installation. Alternatively, the projections may be spaced
sufficiently far apart that they do not laterally squeeze the
thermal elements, but instead have a protuberance at the distal end
of the projection that extends over the thermal elements in use and
prevents them from riding up the side of the projection and
potentially losing their positioning. Two such projections with
protuberances may be positioned a distance apart that they will not
grip the thermal elements when installed, but have their
protuberances facing each other such that the distance between
protuberances is less than the diameter of the thermal element.
Thus the thermal elements may be squeezed or snapped into position
between the projections, but will not easily squeeze back out.
[0009] While the remainder of this document discusses underfloor
heating systems, it will be appreciated that the principles
discussed apply equally to installations in other surfaces such as
walls and ceilings. Also, fluid based systems that achieve heat
exchange by flowing a liquid (typically water) through pipes can be
used for cooling as well as heating. It will be appreciated that
while the remainder of this document is more focused on heating
installations, the principles also apply equally to cooling
systems.
[0010] According to a first aspect, the invention provides a
support structure for a heating or cooling system, comprising: a
plurality of projections designed to be capable of retaining one or
more thermal elements positioned adjacent thereto; wherein the
plurality of projections are positioned so as to form a first set
of substantially parallel undulating channels, each channel having
one of said projections forming at least a part of the inner radius
of each undulation; and wherein each projection has a recess formed
in a side wall thereof facing said channel.
[0011] The undulations of the channel ensure that a thermal element
positioned in the channel will make contact with the projections
each time it has to bend around one, while not requiring the
spacing of the projections to squeeze the thermal element. Thus the
thermal element can be held securely without any play (unwanted
lateral movement) in a channel that is slightly wider than the
thermal element. The recesses in the channels at the contact points
also restrict movement in the vertical direction, thus preventing
the thermal element from `popping out` of the channel, while not
requiring any restriction narrower than the thermal element. In a
traditional installation, the snap-fit mechanism uses an opening
narrower than the thermal element so that the thermal element
deforms to pass through the opening, then elastically returns to
its normal shape and size once in the channel By contrast, with the
present invention the recesses are spaced along the channel so that
the thermal element is only retained by one recess at any
particular point along its length. Moreover, the undulations of the
channel (and thus of the thermal element within the channel) cause
the thermal element to be held within the recess (and thus retained
within the channel, prevented from popping out) by the natural
tension of the thermal element without having to be passed through
a restriction that causes deformation. This has the benefits of
easing the laying of the thermal elements (less force required to
push it into the channel) and less wear on the thermal element by
deformation (leading to longer service life). While this wear has
not generally been considered to be an issue to date, reducing or
removing this installation stress should increase the service life
of the product by increasing the average time to failure. As
repairs can be quite disruptive, the service life is an important
feature of any such system.
[0012] It will be appreciated that the recess on the projection on
the inner radius of the channel may be the only recess present at
that location along the channel, i.e. it is preferred that there is
no recess on a projection immediately opposite, facing the channel
on its outer radius (i.e. facing the outside of the curve or
undulation). While the presence of such a recess is not
problematic, there is no need for it as the thermal element is held
in contact with the projection on its inner radius and thus held
within the recess there without further aid. Particularly as the
channel is preferably slightly wider than the thermal element, the
outer radius on an undulation of the thermal element would not come
into contact any projection present there.
[0013] The recess is preferably a dent or notch or hollow in the
otherwise substantially vertical side wall of the projection. The
side wall is preferably vertical for structural reasons (it is
normally designed to support the weight of an installer walking on
the mat, i.e. on the projections). Forming a dent or notch or
hollow in the middle of the side wall (rather than for example
forming an overhang at the top of the projection) is robust,
retaining the structural strength of the projection (by contrast an
overhang at the top may be bent or broken easily).
[0014] The undulating channels may alternatively be termed `wavy`
channels. The undulations are essentially curved zigzags back and
forth from one side to the other, i.e. the channel may be
considered to be formed from a series of curves in alternating
directions. The curves are preferably of relatively large radius,
i.e. gentle curves rather than tight curves so as to place minimal
stress on the thermal elements. A large radius of curvature may be
considered to be larger than the diameter of the thermal element
(thus larger than the width of the channel), preferably much
larger, e.g. the radius of curvature may be greater than 5 times or
10 times the diameter of the thermal element (or the width of the
channel).
[0015] Preferably the projections also form a second set of
undulating channels, each channel having one of said projections
forming at least a part of the inner radius of each undulation. The
first set of undulating channels may be substantially perpendicular
to the second set of undulating channels. Such a regular array or
grid of channels is useful for laying the thermal elements therein
in a pattern that achieves good coverage of the surface (e.g.
floor) so as to provide good even heating or cooling of the surface
across the required area. Preferably the first and second sets of
undulating channels together encompass a regular rectangular grid.
In other words a rectangular grid (a virtual one) could be drawn
entirely within the channels (including both the first and second
sets) without intersecting any of the projections, the grid being
rectangular and regular, for example a square grid in particularly
preferred symmetrical embodiments. This requirement places a
restriction on the amount of undulation in the channels as the
amplitude of the undulations cannot exceed the width of the channel
without crossing (blocking) the virtual grid. It also places an
overall straightness restriction on the channels such that on
average they follow the straight lines of the grid. This is
convenient for regular patterns of laying thermal elements and is
useful for matching the geometry of most rooms (most rooms being
generally rectangular or at least with perpendicular walls. It will
also be appreciated that the amplitude of the undulations is
preferably greater than the difference between the width of the
channel and the diameter of the thermal element as if this is not
the case then the thermal element may not be constrained to
undulate with the channel but could instead take a straight path
down the middle, avoiding contact with the projections. It is
further preferred that the amplitude of the undulations is less
than 30% of the wavelength of the undulations, more preferably less
than 10% of the wavelength of the undulations. This ensures that
the increase in the required length of thermal element per unit
length of the support structure is kept low. For example, with the
amplitude less than 30% of the wavelength, the installed length of
thermal element is no more than 1.05 meters per meter of support
structure (assuming a straight run of thermal element). With the
amplitude less than 10% of the wavelength, the installed length can
be kept to no more than 1.005 meters per meter of support
structure.
[0016] The channel may be sized appropriately for any suitable
thermal elements. For example electrical heating wires may be
narrower than fluid-carrying conduits (hoses or pipes) and the
structure can be designed and sized appropriately for different
thermal elements. In some particularly preferred embodiments the
channel is sized to accommodate a thermal element with a diameter
at least 2 mm.
[0017] It is preferred to design the projections and the channels
for minimal contact between the projections and the thermal element
beyond what is required for retaining the thermal element securely.
In use, after the thermal element has been laid in the channels, an
adhesive compound (e.g. a tile adhesive) is poured aver the
structure so as to fill the gaps in the channels and surround the
thermal element and thereby assist in conduction and distribution
of heat from the thermal element to the overlying surface. The
projections are typically hollow (typically moulded or vacuum
formed) and thus do not contain a heat conductive substance and
instead provide an insulating volume. Therefore contact between the
thermal element and the projection is preferably minimized so as to
improve overall heat conduction.
[0018] It is possible for a large projection to extend between
adjacent channels and to have two recesses, one on each of two
opposite sides (or indeed four recesses on four sides, each facing
one channel). However such large projections can result in large
areas without thermally conductive filler (e.g. tile adhesive) and
thus can negatively impact thermal distribution. Therefore in
preferred embodiments the projections are grouped into pairs, the
recesses of the two projections facing adjacent undulating channels
of either the first set of channels or the second set of channels.
Each pair of projections is preferably two distinct projections
with a gap between them through which filler material can flow and
through which thermal energy can be transmitted so as to improve
thermal distribution to the areas between adjacent channels (i.e.
intermediate between two thermal elements).
[0019] In some preferred embodiments each projection of the pair is
formed as a curve, the two curves partially surrounding a central
space. The outer radius of each curved projection then forms the
inner radius of the undulating channel Therefore the recess is
preferably formed in that outer radius to from the contact point
and retaining means for a thermal element placed in the
channel.
[0020] The shape of the projections has a particular benefit that
in use they make essentially (or very close to) point contact with
the thermal element(s) while the thermal elements are running in
one of the aforementioned channels. A greater contact area will
only result when a thermal element winds around a projection when
changing direction (e.g. at a 90 degree bend). This reduction in
contact area between the thermal elements and the support structure
results in a greater area of contact between the thermal elements
and thermally conductive filler that is subsequently provided
around the thermal elements, e.g. adhesive or leveling compound.
The thermally conductive filler conducts heat much more efficiently
across the installation than material of the support structure and
therefore this arrangement results in better heat transfer, fewer
hot spots and cold spots, lower thermal gradients and thus lower
stresses within the structure.
[0021] The open and regular grid arrangement of channels together
with the low contact area achieved with the projections also
ensures that there are many easy heat flow paths for heat to be
conducted around the structure. The channels that are not used to
accommodate thermal elements instead provide heat conduction paths
around the structure.
[0022] In order to form the undulations of the channels, each pair
of projections preferably forms a structure that is wider in one
dimension that separates two inner channel diameters than it is in
a perpendicular dimension that separates two outer channel
diameters. The combined structure of the pair thus forms a bulge
around which two undulating channels curve in a mirror-image
manner. It will be appreciated that in other embodiments the
combined structure of the pairs could be generally circular
(forming two arcs of a circle, thereby still allowing thermal
distribution to the middle). Alternating large radius circles and
small radius circles in a chequerboard pattern could be used to
form the undulating channels. However, it is preferred that the
same sized projections are used throughout, i.e. that each pair of
projections has essentially the same shape.
[0023] Thus in some particularly preferred embodiments each pair of
projections can have one of two orientations, one orientation being
a ninety degree rotation of the other orientation, and wherein the
pairs are arranged on the support structure in a rectangular grid
with the orientations set according to a chequerboard pattern. With
this arrangement, and in particular with the generally elliptical
or bulging shape described above, the same size and shape can be
used for all pairs of projections, with only the orientation
changing. This makes for an even pattern with more uniform thermal
distribution across the whole surface (e.g. across a whole
floor).
[0024] While the support structure as described above can be used
on its own, attached to the underlying subfloor directly via an
adhesive layer, it is preferred that the support structure further
comprises a stress mitigation layer on the underside of the
structure, i.e. to lie in between the support structure and the
subfloor. Thus it will be appreciated that the stress mitigation
layer is provided on the side opposite the castellations. The
stress mitigation layer accommodates the differences in thermal
expansion coefficients between the subfloor and the support
structure as well as accommodating any shrinkage during the drying
out process. The stress mitigation layer may be a fabric layer
(such as a fleece layer) that is designed to tear under stress,
thus relieving local stress and spreading it over a larger area.
Such a fabric anti-fracture layer is provided underneath the
support structure and is bonded to the sub-structure. This fabric
layer is designed to tear upon expansion of the support layer,
relieving some of the stress while retaining adequate bonding to
the sub-structure. Alternatively the stress mitigation layer may be
a viscous layer that can flow and move with the surrounding
structures, within its own plane, without tearing and losing
contact. Any microtears are sufficiently small that they self-heal
quickly once the movement has stopped.
[0025] A typical installation on a floor includes a subfloor which
may be wood or concrete or may be a tile backer board. Wood and
concrete are permeable, allowing moisture to escape, but a tile
backer board is generally not, particularly the kinds used in wet
rooms such as bathrooms or shower rooms. Above the subfloor, a
layer of adhesive or a stress mitigation layer is provided, then
the support structure for the thermal elements is on top of the
stress mitigation layer. Tile adhesive is applied on top of the
support structure and thermal elements and finally tiles or
laminates are laid as the upper main floor surface.
[0026] Tile adhesives come in two different types. The first type
is a dry powder to which water is added. A reaction takes place
causing hardening and then the excess water typically dries out
over time. The second type is a wet ready-mix which is applied
straight from a tub and hardens by drying out. With the first type
(dry-type) of adhesive if the water cannot escape (i.e. because
there is no permeable escape route) then the water simply remains
in the hardened structure with no ill effects. However with the
second type (wet-type) of adhesive if the water cannot escape then
the adhesive does not harden. With small tiles, there is an escape
route for water through the grout between tiles, which is generally
permeable. However, with larger tiles and correspondingly less
grout there is insufficient area for the water to escape in a
timely fashion. While the moisture will escape eventually, it will
take significantly longer than the advised time (stipulated by the
adhesive manufacturer) and significantly longer than is practical
for installation (for example it is normally advised not to walk on
the final surface until the adhesive is dry, so long drying times
are inconvenient if not outright impractical. If there is no other
route for water to escape then the adhesive will not harden causing
installation failure. As the support structure for thermal elements
is typically impermeable (typically made from plastics), this has
traditionally prohibited the use of wet-type adhesives with larger
tiles. The support structure is generally formed without through
holes so as to prevent the tile adhesive above the structure
bonding to the floor below through those holes. Such bonding would
risk cracking or damage to the floor or thermal elements due to
thermal expansion differences. In other words such bonding would
prevent any stress mitigation layer form functioning properly to
absorb or alleviate stresses. Thus the support structure has to
date provided a water impermeable layer in the middle of the
structure preventing any possibility of drying out of the adhesive
that is provided above that structure. Thus the combination of such
a structure with larger tiles or other impermeable flooring
materials has meant that the wet-type adhesive cannot be used and
that although the dry-type adhesive will set, it will retain the
water used to make it.
[0027] In preferred embodiments of the invention the support
structure comprises perforations that make the support structure
breathable. In other words the perforations make the support
structure permeable to water. It has been recognized that the
perforations can be formed without risk of through-hole bonding. In
some embodiments the support structure further comprising a fabric
stress mitigation layer on the underside of the structure and the
perforations penetrate through the fabric layer but have a diameter
of no more than 2 mm, preferably no more than 1 mm. The small
diameter of the hole(s) prevents the adhesive from above the
structure (i.e. the adhesive that surrounds the thermal elements)
from seeping through to the underside of the structure and creating
unwanted through-bonds. The advantage of making holes through the
main support structure and the stress-mitigation fabric layer is
that the holes can then be formed by a straight-forward punching or
drilling process after formation and cooling of the support
structure. The fabric layer is typically applied to the back of the
main support structure while the plastics of the main support
structure is still hot so that the fabric layer (typically a
polypropylene fleece layer) partially melts and adheres before
cooling.
[0028] Alternatively, the structure may comprise a fabric stress
mitigation layer on the underside of the structure and also
comprise at least one hole through the main support structure that
does not penetrate the fabric layer, said hole having a diameter of
at least 3 mm, preferably at least 5 mm, more preferably at least
10 mm, and in some embodiments at least 20 mm. The larger hole(s)
allows for much more efficient transport of water across the
support structure. However, by ensuring that the fabric layer is
not penetrated by the large hole, the adhesive on the upper side of
the structure is kept separated from the subfloor by the fabric
layer so that no through-bonding occurs.
[0029] With a perforation design of 3.times.1 mm diameter holes per
pattern repeat (pair of projections) the `specific area` of the
perforations is approximately 2.5.times.10.sup.-3 m.sup.2 of hole
per m.sup.2 of mat (m.sup.2/m.sup.2).
[0030] A single 5 mm diameter hole in the center of each pattern
repeat (between the pair of projections) would give a specific area
of approximately 20.times.10.sup.-3 m.sup.2/m.sup.2.
[0031] With a single 20 mm diameter hole in the center of each
pattern repeat the specific area would be approximately
335.times.10.sup.-3 m.sup.2/m.sup.2.
[0032] The large hole(s) can be formed at any point on the
structure. For example, holes in the top of the projections that
hold and guide the thermal elements are suitable. However, holes in
the top of these projections are not aesthetically pleasing and may
put off customers due to a perceived reduction in strength.
Therefore as an alternative, it is preferred that the hole is
formed in a separate projection. As described above, due to the
bonding of the fabric layer before cooling, it is difficult to form
holes in the lowest surface of the support structure (meaning the
lowest surface when in use, i.e. closest to the underlying
subfloor) without also perforating the fabric layer (which would
risk through-bonding). Therefore forming a dedicated projection
that is separated away from the fabric layer allows a post-cooling
process such as punching or drilling to form the hole in the
dedicated projection without contacting or breaking the fabric
layer.
[0033] If the support structure is formed by moulding then it may
be possible to form holes directly as part of the moulding process.
However, in preferred embodiments the support structure is formed
by vacuum forming. Vacuum forming does not normally lend itself to
the production of holes, but in the case of the dedicated
projections described above, the hole may be formed by applying a
stronger vacuum in the area the dedicated projection, strong enough
to tear the plastic at that point thereby creating the hole as
desired. The fabric layer can then still be applied during cooling
as normal.
[0034] With the support structure having holes that allow water to
pass through, the wet-type adhesive can be used above the support
structure even with large tiles or other impermeable flooring
materials as the moisture can escape down to the sub-floor which is
typically concrete or wood and is permeable, thus allowing the
wet-type adhesive to dry out and function properly.
[0035] The support structure may be made from a variety of
materials, but is preferably a plastic material with sufficient
rigidity to withstand the weight of a reasonably heavy decorative
floor structure (such as stone tiles) with additional loads from
normal use (furniture or people walking on top of it).
[0036] There is a general misconception amongst installers that the
smooth surface of plastic support structures does not provide a
good bond for the adhesive or screed poured over the top. While
tests have shown that a good bond is indeed achieved, it may in
some embodiments be preferred to add texture to the upper surface
of the support structure so as to provide an additional key for the
adhesive or screed. Preferably the surface of the projections is
textured. The texture may be applied in any of a number of ways
such as by moulding or surface imprinting during a vacuum forming
process, or by etching or grit-blasting after formation of the main
structure. One way to form the texture may be to apply fibres to
the surface before cooling so that they partially melt and stick to
the surface, but do not fully melt so as to leave some surface
texture. The fleece fibres of the same type as the fabric
stress-mitigation layer may be used. This can be particularly
economical where the fleece fabric layer is also being used due to
bulk buying or by using off-cuts or wastage from applying the
fabric layer.
[0037] The invention also extends to a method of forming a support
structure for a heating or cooling system, comprising: forming a
plurality of projections designed to be capable of retaining one or
more thermal elements positioned adjacent thereto; wherein the
plurality of projections are positioned so as to form a first set
of substantially parallel undulating channels, each channel having
one of said projections forming at least a part of the inner radius
of each undulation; and wherein each projection has a recess formed
in a side wall thereof facing said channel.
[0038] It will be appreciated that all of the preferred and
optional features described above in relation to the apparatus also
apply equally to the method of making it.
[0039] The use of holes in the support structure for allowing water
transfer is believed to be independently inventive. Therefore
according to another aspect, there is provided a support structure
for a heating or cooling system, comprising: a castellated mat
having a plurality of projections on one side; and a stress
mitigation layer formed on the other side of the mat; wherein the
castellated mat has at least one hole therethrough that does not
penetrate the stress mitigation layer.
[0040] Again, the preferred and optional features described above
also apply here. Therefore the support structure preferably
comprises a fabric stress mitigation layer on the underside of the
structure, and the perforations may penetrate through the fabric
layer but have a diameter of no more than 2 mm. Alternatively the
structure may comprise at least one hole through the support
structure that does not penetrate the fabric layer, said hole
having a diameter of at least 3 mm, preferably at least 5 mm,
preferably at least 10 mm, more preferably at least 20 mm. This
hole may be formed in a separate projection.
[0041] According to another aspect, there is provided a method of
forming a support structure for a heating or cooling system,
comprising: forming a castellated mat having a plurality of
projections on one side; and providing a stress mitigation layer on
the other side of the mat; forming at least one hole through the
castellated mat that does not penetrate the stress mitigation
layer.
[0042] The use of a textured surface is also believed to be
independently inventive. Therefore according yet another aspect,
there is provided a support structure for a heating or cooling
system, comprising: a castellated mat having a plurality of
projections on one side; wherein the surface of the projections is
textured.
[0043] Once again, the preferred and optional features described
above also apply here. For example the texturing may be provided by
adhering particles such as fibres, particularly fleece fibres to
the surface of the mat.
[0044] According to another aspect there is provided a method of
forming a support structure for a heating or cooling system,
comprising: forming a castellated mat having a plurality of
projections on one side; wherein the forming comprising texturing
the surface of the projections.
BRIEF DESCRIPTION OF THE FIGURES
[0045] Preferred embodiments of the invention will be described, by
way of example only, and with reference to the accompanying
drawings in which:
[0046] FIG. 1 shows a perspective view of a first embodiment of a
castellated mat support structure;
[0047] FIG. 2 shows a plan view of the mat of FIG. 1;
[0048] FIG. 3 shows a side view of the mat of FIG. 1;
[0049] FIGS. 4a and 4b show cross-sections through a castellated
mat;
[0050] FIG. 5 shows a perspective view of a second embodiment of a
castellated mat support structure;
[0051] FIG. 6 shows a plan view of the mat of FIG. 5;
[0052] FIG. 7 shows a side view of the mat of FIG. 5;
[0053] FIG. 8 shows a perspective view of a third embodiment of a
castellated mat support structure;
[0054] FIG. 9 shows a plan view of the mat of FIG. 8;
[0055] FIG. 10 shows a side view of the mat of FIG. 8;
[0056] FIG. 11 shows a pair of main projections with a central
additional projection;
[0057] FIG. 12 shows the structure of FIG. 11 with a hole formed
through the additional projection;
[0058] FIG. 13 shows an alternative to FIG. 12 with multiple holes
formed through the additional projection;
[0059] FIG. 14 shows an alternative structure with projection
through-holes;
[0060] FIG. 15 shows a single projection with a large central hole;
and
[0061] FIG. 16 shows a textured mat.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0062] FIGS. 1-3 show a first embodiment of a castellated support
structure 1 in the form of a mat. The mat may take the form of
sheets that can be laid adjacent to one another or a roll that can
be rolled out onto a desired surface. Either way the mat can be cut
to size and shape for any particular installation.
[0063] The mat 1 is typically used as an intermediate structure in
underfloor heating installations and provides a structure around
which a heating element can be wound while holding the heating
element in place. The mat 1 also provides a rigid structure that
can protect the heating element from being damaged, e.g. crushed
during installation by installers walking around on the mat 1.
[0064] While the remainder of this description discusses a heating
element in an underfloor heating installation, it will be
appreciated that the mat is equally useful for a cooling element
such as a conduit to carry a cold fluid and absorb heat from the
room. It will also be appreciated that the installation is not
limited to floors, but could equally well be installed on a wall or
ceiling. It will also be appreciated that underfloor heating
systems can either be fluid-based (often termed hydronic) in which
a hot liquid is pumped through a fluid carrying conduit, or
electrical in which an electrical current is passed through a
heating wire to generate heat. The mat 1 can be used for any of
these installations. The heating conduit, cooling conduit or
heating wire are generally referred to as a thermal element.
[0065] FIG. 1 shows a support structure (mat) 1 with a thermal
element (an electrical heating wire in this particular embodiment)
2 which is flexible and which has been laid in channels 3, 4 which
are formed between projections 5. The projections have a side wall
6 with a height greater than the diameter of the thermal element 2
so that the channels 3, 4 are deeper than the thermal element 2 and
the thermal element 2 is thus fully accommodated in the channels 3,
4. The thermal element 2 thus lies underneath the upper surface of
the mat 1 and is protected from footfall on top of the mat 1.
[0066] As can best be seen in FIG. 2, the channels 3, 4 are
undulating in the sense that the constrictions that form each
channel 3, 4 are not all perfectly in line, but rather are offset
alternately in opposite directions when viewed along the length of
the channel 3, 4. Therefore a thermal element 2 laid in the channel
3, 4 undulates back and forth across a mid-line of the channel 3, 4
as it is deflected by the projections 5 on either side of the
channel 3, 4. This undulation allows the thermal element 2 to be
held in contact with the side walls 6 of a number of the
projections 5, but without being pinched between them and without
requiring overhanging lips to hold the thermal element 2 in the
channel 3, 4. Instead, the channel 3, 4 can be formed to be wider
than the diameter of the thermal element 2, thus avoiding pinching,
while still ensuring that the thermal element 2 is contacted on
both sides thereby holding it securely within the channel 3, 4.
Without such grip on both sides there is a risk that the thermal
element 2 could pop out of the channel 3, 4 which is inconvenient
as it requires relaying of the thermal element 2 and also risks
damage to the thermal element 2 underfoot while not protected in a
channel 3, 4.
[0067] For added security, i.e. for better retention of the thermal
element 2 within the channel 3, 4, it is preferred that a small
recess 7 is provided on the projections 5 at the point of contact
with the thermal element 2. This recess ensures that as the thermal
element 2 is diverted around the projection 5, it sits in the
recess 7 and is thus retained from above by a part of the
projection 5 that overlies the thermal element 2. Note however that
as this recess 7 is only ever present on one side of the channel 3,
4 at one time and as the channel 3, 4 is wider than the thermal
element 2, the thermal element 2 is not pinched as it is pressed
down into the channel 3, 4 and thus does not suffer any potential
damage during this process.
[0068] The portion of the thermal element 2 that lies in channel 4a
in FIG. 2 is caused to undulate by four projections 5 which have
been labeled A, B, C and D in FIG. 2. The projections A and C lie
on one side of the thermal element 2, deflecting it in one
direction (towards the top of the page), while projections B and D
lie on the opposite side of the thermal element 2, deflecting it in
the opposite direction (towards the bottom of the page). Therefore,
with reference to the page of FIG. 2, the thermal element undulates
from left to right over projection A, under projection B, over
projection C and under projection D. The contact points of the
projections A, C interleave with those of projections B, D along
the length of the thermal element 2. It can be appreciated from
this illustration that the outer radius of each projection A, B, C,
D forms the inner radius of the undulations of thermal element 2
placed in channel 4a. The outer radius of the thermal element 2
does not make contact with the projections that are adjacent to it
(best seen in FIG. 4).
[0069] As can be seen in FIGS. 1 and 2, two sets of undulating
channels 3, 4 are formed the first set 3 is perpendicular to the
second set 4. The first set of channels 3 comprises a number of
substantially parallel channels, e.g. 3a, 3b, 3c. Similarly, the
second set of channels 4 comprises a number of substantially
parallel channels, e.g. 4a, 4b, 4c. The term "substantially" here
allows for the fact that adjacent channels in a set or not exactly
parallel. For example, in the design of FIGS. 1-3, the undulations
in two adjacent channels 3a, 3b are a mirror image of each other
such that they undulate towards and away from each other as they
pass along the length of the mat, i.e. there are points in adjacent
channels that are closer together than other points in the same
adjacent channels. Thus the adjacent channels 3a, 3b (and also 4a,
4b or 3b, 3c or 4b, 4c) are not exactly parallel.
[0070] The two sets of channels 3, 4 together encompass a
rectangular grid 8 which is shown in FIGS. 1-3 by way of
illustration but need not actually take any form or be marked on
the mat 1 in any way. The grid 8 is formed from straight lines at
right angles to each other and illustrates the relative positioning
of the projections 5 and how they form the undulating channels 3,
4. Looking at the grid line that lies in the channel 4a at the top
of FIG. 2, it can be seen that the left-most projection 5a that
lies above the grid line is much closer to the grid line than the
two left-most projections 5b, 5c that lie below the grid line.
Together these three projections 5a, 5b, 5c form the left-most
constriction that defines the channel 4a. The next left-most
constriction is again formed by three projections 5d, 5e, 5f, but
this time projection 5d lies below the grid line while projections
5e and 5f lie above it and the projection 5d below the grid line is
much closer to the grid line than the two projections 5e, 5f above
it. Thus these two left-most constrictions are centered on opposite
sides of the grid line and hence cause the channel 4a to undulate
or oscillate along the grid line as it passes from left to
right.
[0071] The projections 5 are arranged in pairs. For example
projections 5b and 5c form a pair. Similarly projections 5e and 5f
form a pair. Each pair of projections 5 lies between two adjacent
channels of the first set of channels 3 and also between two
adjacent channels of the second set of channels 4. Each projection
5 of the pair forms a contact point on a channel 3, 4 such that the
two projections 5 of the pair form contact points on adjacent
channels 3, 4 of one set of channels, but not both. Thus if a pair
of projections 5 form contact points on a channel of the first set
3, they do not form contact points on a channel of the second set 4
and vice versa. Recesses 7 are formed at these contact points as
discussed above. Each pair of projections is thus together slightly
elliptical, having a wider dimension between the outer radii of the
two projections 5 that form contact points with the adjacent
channels (and have recesses 7 formed therein) than the dimension
that does not contact the perpendicular channels.
[0072] The two projections 5 of a pair are curved such that each
forms an arc around a central region 9. The two projections 5 of
each pair are separated from each other so as to form a pathway 10
into the central region 9. These pathways 10 allow heat to be
conducted from the thermal element 2 more evenly across the surface
of the mat 1 as a whole, avoiding cold spots that might otherwise
be formed between channels 3, 4. The curved nature of the
projections 5 allows them to guide the thermal element smoothly
between channels 3 of one set and channels 4 of the perpendicular
set, thus allowing changes of direction of the thermal element 2 so
that it can be laid back and forth across the mat 1 to cover a
whole floor.
[0073] It may be noted that the rectangular grid 8 lies entirely
within the channels 3, 4, i.e. the undulations caused by the
projections 5 do not cause a thermal element 2 placed within the
channel 3, 4 to deviate by more than the width of the thermal
element 2. This puts a restriction on the amplitude of the
undulations so as to minimize the stress placed on the thermal
element 2, while also minimizing the increase in length of thermal
element 2 that is required by the undulations but also ensuring
that the thermal element 2 is still securely held in place.
[0074] As can best be seen in FIGS. 1 and 2, the projections 5 can
be arranged into pairs in two different orientations so that one
orientation provides contact points with one set of channels 3,
while the other orientation provides contact points with the other
set of channels 4. The projections 5 are arranged such that these
two orientations are interleaved like the squares of a
chequerboard, e.g. with one orientation occupying the black squares
and the other orientation occupying the white squares. Thus each
pair is directly adjacent (on the opposite side of a single
channel) to a pair of the other orientation.
[0075] FIG. 4a shows a cross-section taken through two adjacent
pairs of projections 5 and showing the thermal element 2 in contact
with the projection 5d while not being in contact with the
projection 5f. The thermal element 2 (e.g. heating wire) is seated
in recess 7 in the outer diameter of curved projection 5d and is
therefore constrained from upwards movement by the vertical overlap
of the thermal element 2 and the projection 5 formed in this
region. It can be seen that the thermal element 2 is not
constrained by any similar overlap on the opposite side, i.e.
adjacent to projection 5f. FIG. 4b shows a similar view, but taken
at an angle (along the line IV-IV in FIG. 2) rather than
substantially parallel to the channel 4 so as to take a section
through the narrowest point of the channel between the outer radius
of the large-radius part of one projection and the outer radius of
the small-radius part of an adjacent projection (on the opposite
side of the channel 3). It can be seen in FIG. 4b that the thermal
element 2 is narrower than this narrowest part of the channel, i.e.
the thermal element 2 is in contact with the large radius of the
projection on the right, but there is a gap between the thermal
element 2 and the small radius of the projection on the left.
[0076] FIGS. 5-7 are similar to FIGS. 1-3, except that for clarity
the thermal element 2 is not shown in these figures. FIG. 7 is a
side view looking down the length of channels 3. It will be
appreciated that from this viewpoint two rows of pairs of
projections can be seen, one behind the other. The wider dimension
of a pair of projections in the rear row can be seen extending out
beyond the narrower dimension of a pair of projections in the front
row. This is highlighted on the right hand side of FIG. 7 where
reference numeral 6' shows the vertical side wall of the projection
in the front row, while reference number 7' shows the recess in the
side wall of the projection in the rear row. It can clearly be seen
that the width of the projection 5 between side walls 6' in front
is less than the distance between the recesses 7' of the pair of
projections behind. FIGS. 5-7 also show perforations 11 that are
formed through the support structure 1 so as to provide a liquid
transfer path from one side to the other of the support structure
1. These perforations 11 allow any adhesive that is applied above
the support structure 1 to dry out by losing moisture through the
perforations 11. As in existing installations, any evaporation path
that allows moisture to escape upwards, e.g. between tiles, is
still viable.
[0077] However, the perforations 11 allow wet-type adhesives to be
used even when there is no (or there is insufficient) moisture
escape route upwards from the support structure. Instead, moisture
can escape by travelling across the membrane support structure 1
from a top side (tile side or floor side) to the bottom side
(sub-floor side) and can escape through normal moisture escape
paths e.g. through a wooden or concrete sub-floor structure.
[0078] The perforations 11 are formed in the structure 1 by
punching or drilling through the finished structure. Thus the
perforations 11 are formed through the support structure 1 itself
as well as through any stress mitigation layer formed on the
underside thereof (as best seen in FIG. 7). For example where a
fabric layer such as a fleece layer 12 is formed on the back of the
support structure 1, the perforations pass through the support
structure 1 (typically plastic) and through the fabric layer 12.
The diameter of the perforations 11 is kept sufficiently small that
these through-holes do not allow adhesive to pass through from the
top to the bottom and form a rigid connection across the support
structure 1. Such a rigid connection would prevent the
stress-mitigation layer from accommodating relative movement of the
support structure 1 and the sub-floor, e.g. due to thermal
expansion variations. The perforations are no more than 2 mm in
diameter to ensure no such rigid connection.
[0079] As is shown in FIGS. 5-7, numerous perforations may be used
to make up for their small size, regularly distributed across the
surface of the support structure 1. In the embodiment of FIGS. 5-7
the perforations are formed along one set of channels 3 at a rate
of three perforations per pair of projections 5 (i.e. two
perforations between each perpendicular channel of the second set 4
and one on the intersection of perpendicular channels). However, it
will be appreciated that this is purely an example and any other
number and/or arrangement of perforations could equally well be
used.
[0080] FIGS. 8-10 are similar to FIGS. 1-3, except that for clarity
the thermal element 2 is not shown in these figures. Also, FIG. 10
is a cross-section through the support structure 1 rather than a
side view as this better shows the construction. The different
hatchings on the cross-section illustrate the different pairs of
projections (the different orientations being represented by
different hatching).
[0081] FIGS. 8-10 illustrate an alternative to FIGS. 5-7 (although
the two techniques could be used together) which uses larger holes
13 for transferring moisture from one side of the support structure
1 to the other side. The larger holes 13 can have a larger area
than the perforations 11 and can thus allow a faster rate of
moisture transfer across the structure 1. However, a larger area
hole means that there is a risk of adhesive bonding across the
structure 1 which could prevent the stress-mitigation layer from
operating correctly. Thus the larger holes 13 are formed only
through the support structure 1 and not through the stress
mitigation layer 12 (in this embodiment a fabric (fleece) layer
bonded to the underside of the support structure 1). As the stress
mitigation layer 12 remains unbroken, adhesive from the upper side
of the structure 1 is prevented from bonding to the underlying
sub-floor and thus the stress-mitigation layer remains in place to
accommodate relative movement due to differing thermal
expansion.
[0082] In order to allow the holes 13 to be formed without damage
to the stress mitigation layer 12, the holes 13 are formed in
projections 14 which project away from the stress mitigation layer
12. As a gap is present between the upper surface of the projection
14 and the stress mitigation layer 12, it is easy to cut, drill or
otherwise rupture the top of the projection 14 without at the same
time damaging the stress mitigation layer 12. In this embodiment
the projection 14 is a separate projection formed in the central
area 9 between each pair of projections 5, i.e. one such projection
14 can be formed for every two projections 5 on the mat 1.
[0083] In use, when adhesive is applied to the upper surface of the
support structure 1, the adhesive can flow through the holes 13
where it collects between the stress mitigation layer 12 and the
underside of the projection 14. This has an additional benefit of
providing a good bond between the adhesive layer and the support
structure 1.
[0084] FIG. 11 shows a close up of a pair of projections 5 with
perforations 11 formed in the support structure 1. FIG. 12 shows a
close up of a pair of projections 5 with an additional projection
14 and hole 13 formed therein. FIG. 13 shows an alternative version
of FIG. 12 where instead of a single hole 13, a plurality of
smaller holes 13' are formed.
[0085] FIG. 14 shows another alternative to FIGS. 12 and 13.
Instead of forming the hole 13 (or holes 13') in a dedicated
projection, holes 13'' are formed in the tops of the main
projections 5. These holes 13'' can be formed particularly quickly
and easily for example by cutting across the mat 1 after forming.
However, the end result, while perfectly practical, is less
aesthetically pleasing and for this reason may be less
preferred.
[0086] FIG. 15 shows a variation in which a single large projection
15 is used in place of a pair of projections 5. All features of
this single large projection 15 may be the same as for the
combination of the pair of projections 5 except that there are no
paths 10 to conduct heat into the central region of the projection
15. The single large projection 15 has the advantage of allowing a
very large hole 16 to be formed in the top thereof for very
efficient transfer of moisture across the structure 1.
[0087] FIG. 16 shows a textured version of the support structure 21
which is identical to the support structure 1 discussed above
except with the addition of a textured upper surface (the surface
that contacts the thermal element in use). The texture may be
provided by adhering particles such as fibres to the surface of the
mat. Fleece fibres are particularly suitable for this texturing and
provide a keyed surface for good bonding of adhesive to the mat
21.
[0088] It will be appreciated that other variations and
modifications may be made to the examples described above while
still falling within the scope of the appended claims.
* * * * *